Safety cut-off for outboard motor



Dec. 10, 1957 w. E. RANDS ETAL 2,816,136

SAFETY CUTOFF' F OR OUTBOARD MOTOR Filed April 2'7, 1955 United States Patent Ofiice 2,816,186 Patented Dec. 10, 1957 2,816,186 SAFETY UT-OFF FOR OUTBOARD MOTOR William E. Rands, Waterport, and Leo E. Collins, Lyndonville, N. Y.

Application April 27, 1955, Serial No. 504,215 8 Claims. (Cl. 200-52) This invention relates to a safety cut-off for an outboard motor and more particularly to a means for rendering the outboard motor inoperative when its mounting on a boat transom loosens.

As presently constructed, outboard motors have a bracket adapted to fit over the transom of a boat and be clamped thereto by one or more clamping screws which are manually adjustable. During use of the boat with the motor thereon vibrations may tend to loosen the adjustment of the hold-down screws and this has the effect of permitting the outboard motor to jump off the transom when the boat is sharply turned or if the boat is being used on rough water. Also, the hold-down screws may have been inadequately tightened in the first instance. Regardless of the cause for loosening of the hold-down screws, it is obviously desirable to prevent the outboard motor from becoming disengaged from the boatduring use since this usually results in the loss of the motor into the water.

It is therefore the principal object of the present invention to provide a means associated with that employed for normally clamping the outboard motor on the boat transom which is operative to render the outboard motor inoperative when the mounting of the same has become loosened to a predetermined degree.

Another object of the present invention is to provide such safety means which is associated with the electrical circuit of the outboard motor so as to render such circuit ineffectual when the mounting of the outboard motor on the boat has loosened to a predetermined degree.

Another object of the invention is to provide such safety means which, although rendering the outboard motor inoperative when its mounting on the boat transom has loosened to a predetermined degree, yet provides a sufliciently secure mounting of the outboard motor so as toprevent its ready removal from the boat transom.

A further object of the invention is to provide such a safety means which can be readily combined with all types of outboard motors as conventionally constructed.

A further object of the invention is to provide such safety means which are simple and compact in construction and themselves are not likely to get out of order or require repairs.

Other objects and advantages of the present invention will be apparent from the following description and the accompanying'drawings in which:

Fig. lis a side elevational view of an outboard motor equipped with the safety means embodying the present invention and shows the outboard motor mounted on the transom of a boat which transom is fragmentarily illustrated.

Fig. 2 is a fragmentary transverse sectional view thereof taken on line 11, Fig. 2.

Fig. 3 is a wiring diagram of the electrical circuit for one spark plug of the outboard motor as shown in Fig.

1 and this diagram illustrates the manner in which the safety means of the present invention ciated with the motor circuit.

Fig. 4 is a greatly enlarged horizontal transverse sectional view of the switch device which embodies a preferred form of the present invention and illustrating the same in its inoperative condition.

Fig. 5 is a view similar to Fig. 4 but illustrating the switch device in an operative condition effected by a partial separation of certain of its members.

Fig. 6 is an end elevational view, on a reduced scale, of the switch device shown in either Fig. 4 or Fig. 5, viewed from the left end thereof.

Fig. 7 is an exploded view, on a reduced scale, of the various parts which make up the switch device illustrated in either Fig. 4 or Fig. 5.

An outboard motor of a typical conventional design is illustrated in Fig. l and represented generally by the numeral 10. Such motor is shown, as is conventional, as having a transom bracket 11 adapted to fit over the upper end of a boat transom which is represented gen erally by the numeral 12. As is conventional, the transom bracket 11 has a depending base part 13 adapted to engage the outer surface of the transom 12, an inner depending part 14 arranged on the inner side of the transom 12, and in spaced relation thereto, the parts 13 and 14 being connected together at their upper ends by a transverse intermediate part 15 formed integrally therewith. The inner depending part 14 of the transom bracket is provided with an internally threaded hole extending generally normally to the inner face of the base plate 13 and a clamping screw 16 is shown as arranged within this threaded hole and adapted to be turned by a suitable handle 17 arranged at the end of the clamping screw which is outside the clamping bracket. Usually, the other end of the clamping screw, the one arranged intermediate the parts 13 and 14 of the transom bracket, is provided with a head, base or pad which is adapted to be forced against the inner surface of the transom by tightening the clamping screw 16. In the form of outboard motor illustrated in the accompanying drawing, two such clamping screws 16 are shown as associated with the transom bracket 11, this being the conventional number used with outboard motors of current construction, although the invention as now about to be described is not limited to any specific number of clamping screws.

In accordance with the present invention, a switch device indicated generally at 18 in Fig. 1 and embodying the present invention is associated with one of the members of the transom bracket 11 which are arranged on opposite sides of the boat transom so that this switch device can be actuated by the clamping pressure. While the switch device may be mounted on either the base part 13 of the transom bracket 11 or the end of the clamping screw 16, it is preferred to mount such device on the end of the clamping screw as shown in the drawing.

Referring to Fig. 4-, the switch device 1 8 comprises a cup-shaped housing 20 of circular form having a relatively thick transverse wall 21 at one end and cylindrical side wall 22 extending axially from the perimeter of the end wall. Slidably arranged within the bore of the cupshaped housing 20 is another cup-shaped member 23 having a cylindrical side wall 24 and a transverse end Wall 25. The transverse end wall 25 of the inner cupshaped member 23 is shown as being provided with a central counterbored hole 26 in which the reduced end 28 on the end of the clamping screw 16 is arranged. Any suitable means may be employed for connecting the clamping screw 16 and cup-shaped member 23 but as shown, the reduced end 28 is provided with an annular groove in which a split retaining ring 29 is arranged and adapted to prevent withdrawal of the reduced neck form is electrically asso- 3 the hole 26 while permitting the clamping screw 16 to turn while the cup-shaped member 23 remains stationary.

The inner cup-shaped member 23 is telescopically arranged on the outer cup-shaped member 20 to have a limited axial movement relative thereto. Such axial movement is limited and guided by a pair of diametrically opposed radially extending screws 30, 30. Each screw is arranged in an internally threaded hole provided in the side Wall 22 of the outer cup-shaped housing 24) and the inner end of such screw projects inwardly of such wall into a slot 31 provided in the side wall 24 of the inner cup-shaped member 23. Each such slot 31 is elongated in an axial direction of the cylindrical wall 24 and is considerably longer than the diameter of the inner end of the screw 30 and each slot is also closed at its opposite ends. By such an arrangement the cupshaped members 20 and 23 are permitted axial non-rotative movement relative to each other limited in one direction by the inner end face of the wall 24 engaging the inner face of the transverse wall 21, as shown in Fig. 4. The relative movement of the two cup-shaped members 20 and 23 in the other direction or toward separation is limited by one end of the slots 31 engaging the inner ends of the screws 30.

Yielding means are provided for urging the cup-shaped members 20 and 23 apart. Such means are shown as in eluding a relatively heavy helical spring 32. Such spring is shown as having a diameter so as to permit the same to be arranged within the cylindrical side wall 24 of the inner cup-shaped member 23. At one end, such spring 32 bears against the transverse end wall 21 of the outer cup-shaped member 20 and at its other end the spring is shown as exerting a thrust against the transverse end wall 25 of the inner cup-shaped member 23.

The relative position between the cup-shaped members 20 and 23 controls the position of a contact member 33. Such contact member 33 has an enlarged head at one end from which a stem or shank 34 projects in an axial direction. The stem 34 is shown as extending through a hole centrally arranged within the transverse end wall 21 of the outer cup-shaped member and is hushed by a bushing 35 arranged in such hole. Such bushing is made of any suitable insulating material. The enlarged head of the contact member 33 is arranged within an enlarged recess in the end wall 21 which is normally closed by a plug 36 preferably pressed into the enlarged hole. This plug is also preferably made of a suitable non-conductive material. A wire 38 is shown as extending through a radial hole provided in the end wall 21 of the outer cup-shaped member 20 and at its inner end this wire is suitably connected to the contact member 33.

The head of the contact member 33 is adapted to engage the metal body of the outer cup-shaped member 20 immediately surrounding the bushing 35. Such engagement is illustrated in Fig. 5 and represents a closed position of the switch device. The contact member 33 is urged toward this closed position by a helical compression spring 39 which surrounds the inner end of the stem 34 of the contact member which projects into the space between the opposing end walls 21 and 25. At one end the spring 39 bears against the head of the bushing 35 which is shown as being recessed into the inner face of the end Wall 21. The other end of this spring 39 bears against a ring 40 arranged on the stem 34 and this ring is held in place by a pin 41 which extends transversely through the shank 34 and is arranged on the outer side of this ring.

The contact member 33 is adapted to be unseated by the movement of the inner cup-shaped member 23 inwardly of the outer cup-shaped member 20. For this purpose a bridge member 42 also of cup-shaped form and having an outwardly projecting annular flange is arranged on the inner face of the transverse end wall 25 of the inner cup-shaped member 23. The flange 0f the cup- 4- shaped member 42 is shown as being interposed between the end wall 25 and the adjacent end of the spring 32. The raised central portion of the bridge member 42 is shown as having a central hole in which a block of insulating material 43 is arranged as by being press-fitted therein. The block 43 serves as an abutment and is adapted to engage the inner end face of the stem 34 of the contact member 33. When the inner cup-shaped member 23 is forced inwardly of the outer cup-shaped member 20 against the urging of the spring 32, it will. be seen that the abutment 43 pushes the contact member 33 from the position shown in Fig. 5 into the position shown in Fig. 4. Thus conductive contact between the head of the contact member 33 and the body of the outer cup-shaped member 20 is destroyed. The various parts of the switch device 18, with the exception of the plug 36, bushing 35 and abutment block 43, are made of an electrically conductive metal, preferably brass, to minimize corrosion since the device is likely to get wet in use.

The making and breaking of contact between the contact member 33 and the body of the outer cup-shaped member 20 is utilized to control the operativeness of the electrical circuit for the outboard motor. Referring to Fig. 3, the magneto for the motor is represented as having a core 45 and grounded primary and secondary coils 46 and 47, respectively, wound thereon. A one-wire system is shown since the frame of the outboard motor serves as ground. The secondary coil is connected to the spark plug 48 through the line 49. The primary coil 47 through the line 50 is connected to the breaker points represented at 51 which are opened and closed by a cam on the crankshaft of the motor as is well understood by those skilled in the art. A condenser 52 is shown as arranged in parallel with the breaker points 51 and serves to prevent a spark from jumping across the breaker points as they are moved apart. The switch device 18 of the present invention is shown as being grounded at one end to the frame of the outboard motor because of its mounting on the clamping screw 16 and connected at its other end through the wire 38 to the point of connection between the condenser 52 and the line 50 which is intermediate the breaker points 51 and the magneto. It will be seen that when the switch device 18 is closed the switch shorts out the primary coil and therefore renders the same ineffectual.

With a two-cylinder engine having a spark plug for each cylinder, it will be understood that the circuit depicted in Fig. 3 is typical of that for each of the spark plugs, a separate switch device 18 being provided for each spark plug with its respective independent lead 38 as shown in Fig. 2.

Assuming the switch device 18 to be arranged on the end of each of the clamping screws 16 as shown in Figs. 1 and 2, it will be seen that as each screw is tightened the outer end face of the corresponding outer cup-shaped member 20 is forced against the inner face of the transom 12. To prevent slippage between these engaging surfaces the outer face of the member 20 is preferably provided with any suitably roughened surface. As best shown in Fig. 6, such face can be provided with a pair of radially spaced circular ribs 53 which are adapted to be pressed into the transom 20 to provide an interlocking engagement therewith. As the clamping screw 16 is tightened down such screw forces the switch device 18 firmly into engagement with the transom 12. Continued tightening of the clamping screw 16 forces the inner cup-shaped member 23 to move inwardly of the outer cup-shaped member 20 thereby through the abutment member 42 causing the head of the normally closed contact member 33 to break contact with the body of the outer cup-shaped member 20. In this manner the switch device 18 depicted in Fig. 3 is opened. However, should the clamping screw 16 become loosened so that the inner cup-shaped member 23 moves outwardly to a position relative to the outer cup-shaped member as shown in Fig. 5, the contact member 33 under the urging of its spring 39 forces the head of this contact member to engage the body of the outer cup-shaped member 20 thereby closing the switch 18 depicted in Fig. 3. This shorts out the primary coil 46 and prevents the corresponding spark plug 48 from being fired. If one spark plug cuts out there will be a noticeable effect in the sound and drive of the motor which should attract the attention of the operator. If both switch devices cut out their respective spark plugs, the outboard motor will stop entirely since both spark plugs 'will have beenshorted out.

It is a feature of the present invention that notwithstanding the switch device 18 has closed, there is still left in the spring 32 a residual force which will produce a sufficiently secure clamping action of the transom bracket 11 on the transom 12 as to prevent ready removal of the outboard motor from the transom. This is illustrated in Fig. 5 from which it will be seen that the spring 32 is still under compression and the inner ends of the slots 31 have not engaged the screws 30. Of course, if the clamping screw 16 is loosened or backed off to a point where the expansion between the inner and outer cup-shaped members 20 and 23 has been permitted to take place to its fullest extent, being limited by the end walls of the slots 31 engaging the inner ends of the screws 30, the spring 32 will have been rendered completely ineffectual. In use, however, the motor will have stopped before this condition occurs.

it will also be seen that the motor can be placed back in operative condition by merely tightening down the clamping screws 16.

In lieu of arranging the switch devices 18 on the ends of the clamping screws 16, the switch device can be incorporated into the base part 13 of the transom bracket 11 and the clamping screws provided with the usual pads which were removed and replaced by the switch devices in the embodiment illustrated.

From the foregoing it will be seen that the present invention provides a safety means which is simple and compact in construction, which can readily be incorporated in existing designs of outboard motors, and which is operative to render the outboard motor inoperative when its mounting on the boat transom loosens to a predetermined degree where there is danger of losing the motor if it continues in operation.

We claim:

1. In an outboard motor having clamping means for mounting the motor on the transom of a boat and including opposing members bearing against opposite sides of said transom, the combination therewith of means for rendering the motor inoperative when its mounting on said transom loosens, comprising a normally closed switch device arranged on one of said members and adapted to be opened when the pressure of said clamping means exceeds a predetermined amount and means operatively associating said switch device with the electrical circuit of the outboard motor.

2. In an outboard motor having clamping means for mounting the motor on the transom of a boat and including opposing members bearing against opposite sides of said transom, the combination therewith of means for rendering the motor inoperative when its mounting on said transom loosens to a predetermined degree, comprising a switch device arranged on one of said members and having relatively movable parts, a contact member arranged on one of said parts and associated with the electrical circuit of the outboard motor and movable by the other of said parts to render the outboard motor inoperative and yielding means urging said parts toward a relative position opposing such effect.

3. In an outboard motor having clamping means for mounting the motor on the transom of a boat and in- 6 eluding opposing members bearing against opposite sides of said transom, the combination therewith of means for rendering the motor inoperative when its mounting on said transom loosens to a predetermined degree, comprising a switch device arranged on one of said members and having relatively movable parts, a contact member movably arranged on one of said parts and movable by the other of said parts, said contact member being associated with the electrical circuit of the outboard motor and adapted to contact said one of said parts thereby to render the outboard motor inoperative, and spring means so arranged between said parts as to oppose said contact member contacting said one of said parts.

'4. In an outboard motor having clamping means for mounting the motor on the transom of a boat and in cluding opposing members bearing against opposite sides of said transom, the combination therewith of means for rendering the motor inoperative when its mounting on said transom loosens to a predetermined degree, comprising a switch device arranged on one of said members and having relatively movable parts, a normally closed contact member movably arranged on one of said parts, and operatively associated with the electrical circuit of the outboard motor, spring means urging said contact member toward a closed condition, said contact member being adapted to be opened by movement in a given direction of the other of said parts relative to said one of said parts, aand a second spring means urging said parts toward relative movement in a direction opposite to said given direction.

5. A switch device for mounting on the clamping screw of an outboard motor, comprising telescopically arranged cup-shaped members the end wall of one of which is adapted to engage the transom of a boat and the end wall of the other of which is arranged for connection to the end of said clamping screw, a spring interposed between said members and urging them apart, a contact member movably arranged on one of said end walls, means urging said contact member to an operative closed position in which it is in electrical contact with said one of said end walls; an abutment arranged on the other of said end walls and adapted to move said contact memher to an inoperative open position upon movement of said other of said end walls and against the urging of said spring, said contact member being out of electrical contact with said one of said end walls when in said inoperative open position and said contact member being capable of assuming its said operative closed position while said spring is under compression.

6. A switch device for mounting on the clamping screw of an outboard motor, comprising telescopically arranged cup-shaped members the end wall of one of which is adapted to engage the transom of a boat and the end wall of the other of which is arranged for connection to the end of said clamping screw, a spring interposed between said members and urging them apart, said one end wall having a hole therethrough enlarged at its outer end, a bushing of insulating material arranged in said hole, a closure for the outer end of said hole, a contact member having an enlarged head at one end arranged in the enlarged portion of said hole and adapted to contact the body of said one end wall, said contact member also having a stem slidably arranged in said bushing and projecting therethrough, a spring arranged on the projecting end of said stem to urge said head toward contact with said body, and an abutment of insulating material carried by said other cup-shaped member and adapted to engage said stem and push the contact member out of contact with said body.

7. A switch device for mounting on the clamping screw of an outboard motor, comprising telescopically arranged cup-shaped members the end wall of one of which is adapted to engage the transom of a boat and the end wall of the other of which is arranged for connection to the end of said clamping screw, a spring interposed between said members and urging them apart, means limiting the separation of said members, said one end wall having a hole therethrough enlarged at its outer end, a bushing of insulating material arranged in said hole, a closure for the outer end of said hole, a contact member having an enlarged head at one end arranged in the enlarged portion of said hole and adapted to contact the body of said end wall, said contact member also having a stem slidably arranged in said bushing and projecting therethrough, a spring arranged on the projecting end of said stem to urge said head toward contact with said body, a bridge member clamped by said first mentioned spring against said other end wall, and a block of insulating material carried by said bridge member and adapted to engage said stem and push the contact member out of contact with said body.

8. In an outboard motor having clamping means for mounting the motor on the transom of a boat and including opposing members bearing against opposite sides of said transom and also having an electrical circuit including breaker points and a condenser in parallel connected to a magneto coil, the combination therewith of means for rendering the motor inoperative when its mounting on said transom loosens, comprising a normally closed switch device operatively connected to said circuit between said condenser and coil and arranged on one of said members and adapted to be opened when the pressure of said clamping means exceeds a predetermined amount.

References Cited in the file of this patent UNITED STATES PATENTS 2,520,353 Campo et al Aug. 29, 1950 

